川西南高山湖泊沉积记录的过去2000年植被和气候变化

高山湖泊沉积对气候变化敏感，其被广泛地用来重建植被和气候变化历史。重建最近2000年横断山脉地区气候变化，对于理解印度夏季风演化规律及其驱动机制具有重要意义。本项目拟以川西南小相岭两个高山湖泊为研究对象，利用陆生植物残体AMS14C和浅层沉积岩芯210Pb、137Cs测定相结合的年代学方法，建立沉积岩芯高精度的年代标尺。在此基础上，利用孢粉和植物大化石指标，重建近2000年小相岭地区植被演替过程；结合其他环境代用指标（总有机碳、总氮、总磷、生物硅含量、有机质碳氮同位素等），恢复近2000年川西南地区温度和降水变化历史，重点关注典型时期（如中世纪异常期、小冰期和现代变暖时期）温度-降水变化特征。开展区域气候对比分析，揭示过去2000年印度夏季风演化规律。通过与太阳活动、热带太平洋-印度洋海温等指标进行遥相关分析，探讨过去2000年川西南地区气候变化的动力成因。

Alpine lacustrine sediments are sensitive to climatic changes, so it is widely to reconstruct vegetation and climate changes by using alpine lacustrine sediments. The reconstructions of the climate changes in Hengduan Mountain regions during the last 2000 years are of great importance to understand the Indian summer monsoon dynamic mechanisms. In this proposal, we will select two alpine lake records as research objects. We will establish the highly accurate chronological model by the combination of AMS14C method on the terrestrial plant residues and 210Pb-137Cs method on the upper sediments. Based on the accurate chronology, we will use multiple palaeoenvironmental and palaeoecological index (pollen, plant macrofossil, total organic carbon, total nitrogen, biogenic silicon content, etc) to reconstruct the vegetation and climatic changes during the last 2000 years over southwestern Sichuan province, with special focus on the climatic patterns over some typical intervals such as Medieval Warm Period, Little Ice Age, and Current Warm Period. Then we will compare climatic changes over the southwestern China to reveal the Indian summer monsoon evolution law. Lastly, we will compare our climatic index with the forcing like solar variability, ITCZ, tropical Pacific and Indian Ocean sea surface temperature to explore the possible underlying mechanisms on the climate change over southwestern Sichuan province during the last 2000 years.